Photophysical Properties of Emerging 2D Materials

Photophysics is a branch of physical science that underpins a wide range of light-based applications. This field has emerged as a powerful tool for exploring light–matter interactions, enabling researchers to understand the behaviour of materials through optical and optoelectronic properties of light under different environmental conditions and timescales. Recently, the integration of two-dimensional (2D) materials into nanostructure-based devices has played a vital role in enhancing physical and chemical properties, particularly for optoelectronic applications. Since their introduction, 2D ultra-thin materials, with their efficient performance and low cost, have attracted considerable attention as a promising semiconducting material owing to their enhanced stability under ambient conditions as well as tuneable optical and electrical/optoelectronic characteristics associated with layer thickness. The present study explores mechanically exfoliated 2D flakes as active materials for high-performance photodetectors fabricated via electron-beam lithography (EBL). The investigation includes 2D indium selenide (α-In₂Se₃), a layered semiconductor with unique ferroelectric behaviour and a tunable bandgap, where its performance is evaluated both in transistor and photodetector configurations. The results demonstrate thickness-dependent transport and photoresponse characteristics, revealing the potential of α-In₂Se₃ as a multifunctional 2D material for advanced optoelectronic devices. In parallel, efforts focus on hybrid 2D perovskites, which are examined as light-absorbing materials due to their strong excitonic effects and favourable optical properties. Despite their promise, perovskite crystals present significant challenges for device integration, as they are prone to structural degradation under ambient exposure and highly susceptible to the damaging effects of high-energy electron beams during EBL. These limitations often restrict their application to larger-scale devices fabricated by shadow masks or low-resolution patterning methods, which hinders progress toward miniaturized and scalable devices. To address this, lithographic parameters and resist processing are systematically optimized to minimize beam-induced damage, enabling the reliable definition of nanoscale electrodes while preserving the fragile perovskite crystal structure. These advances make it possible to fabricate top-down lithography-based perovskite photodetectors with well-defined device geometries, whose figures of merit, including responsivity, detectivity, and response speed, are systematically evaluated and benchmarked against state-of-the-art devices. In particular, for the first time, I will show how new strategies, such as fast lift-off and mitigating the dose of the electron-beam, contribute to enhancing their optoelectronic performance. Beyond fabrication and performance optimization, device stability is further enhanced through a novel encapsulation method using a beeswax/PMMA layered structure. This encapsulant provides long-term protection against moisture and environmental degradation, allowing the devices to operate stably under water for extended durations. The encapsulated photodetectors are also demonstrated in turbidity sensing experiments, confirming their robustness and versatility for real-world applications.<p></p>

Author dc:creator

• Mohammed Ali S Alshehri (21041459)

• Photophysics
• 2D Materials

Statement dc:rights

• All rights reserved
• Open Access after 2029-03-16

Identifier

10779/exe.31744399.v1

OAI identifier oai:identifier

oai:figshare.com:article/31744399